<?php
class JSSDK {
	private $appId;
	private $appSecret;
	private $file_path;
	
	public function __construct($appId, $appSecret) {
		$this->appId = $appId;
		$this->appSecret = $appSecret;
		//by willson 2015/3/18
		//修改微信提供的类，将缓存jsapi_ticket的文件放在temp目录下
		$this->file_path = '';
		if (defined('ROOT_PATH')) {
			$this->file_path = ROOT_PATH . "/temp/";
			//echo $this->file_path;
			if (!is_dir($this->file_path)) {
				$this->file_path = '';
			}
		}
		//end
	}
	
	public function getSignPackage($url = "") {
		$jsapiTicket = $this->getJsApiTicket();
		
		// 注意 URL 一定要动态获取，不能 hardcode.
		$protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
		if (!$url) $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
		
		$timestamp = time();
		$nonceStr = $this->createNonceStr();
		
		// 这里参数的顺序要按照 key 值 ASCII 码升序排序
		$string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";
		
		$signature = sha1($string);
		
		$signPackage = array(
			"appId"     => $this->appId,
			"nonceStr"  => $nonceStr,
			"timestamp" => $timestamp,
			"url"       => $url,
			"signature" => $signature,
			"rawString" => $string
		);
		return $signPackage; 
	}
	
	private function createNonceStr($length = 16) {
		$chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		$str = "";
		for ($i = 0; $i < $length; $i++) {
			$str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
		}
		return $str;
	}
	
	private function getJsApiTicket() {
		// jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例
		$file_path = $this->file_path . "jsapi_ticket.json";
		if(!file_exists($file_path)){
			$handle = fopen($file_path, 'a') or die("Unable to open file!");
			fwrite($handle, '');
			fclose($handle);
		}
		$data = new stdClass();
		$ticket = '';
		$need_new_token = false;
		$file_contents = file_get_contents($file_path);
		if (strlen(trim($file_contents))<=0) {
			$need_new_token = true;
		} else {
			$data = json_decode($file_contents);
			if ($data->expires_in < time()) $need_new_token = true;
		}
		if ($need_new_token) {
			$accessToken = $this->getAccessToken();
			// 如果是企业号用以下 URL 获取 ticket
			// $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
			$url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
			$res = json_decode($this->httpGet($url));
			if (isset($res->ticket)) {
				$ticket = $res->ticket;
				$data->jsapi_ticket = $ticket;
				$data->expires_in = $res->expires_in + time();
				$fp = fopen($file_path, "w");
				fwrite($fp, json_encode($data));
				fclose($fp);
			}
		} else {
			$ticket = $data->jsapi_ticket;
		}
		return $ticket;
	}
	
	private function getAccessToken() {
		// access_token 应该全局存储与更新，以下代码以写入到文件中做示例
		$file_path = $this->file_path . "access_token.json";
		if(!file_exists($file_path)){
			$handle = fopen($file_path, 'a') or die("Unable to open file!");
			fwrite($handle, '');
			fclose($handle);
		}
		$data = new stdClass();
		$access_token = '';
		$need_new_token = false;
		$file_contents = file_get_contents($file_path);
		if (strlen(trim($file_contents))<=0) {
			$need_new_token = true;
		} else {
			$data = json_decode($file_contents);
			if ($data->expires_in < time()) $need_new_token = true;
		}
		if ($need_new_token) {
			// 如果是企业号用以下URL获取access_token
			// $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
			$url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
			$res = json_decode($this->httpGet($url));
			if (isset($res->access_token)) {
				$access_token = $res->access_token;
				$data->access_token = $access_token;
				$data->expires_in = $res->expires_in + time();
				$fp = fopen($file_path, "w");
				fwrite($fp, json_encode($data));
				fclose($fp);
			}
		} else {
			$access_token = $data->access_token;
		}
		return $access_token;
	}
	
	private function httpGet($url) {
		$curl = curl_init();
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($curl, CURLOPT_TIMEOUT, 500);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
		curl_setopt($curl, CURLOPT_URL, $url);
		
		$res = curl_exec($curl);
		curl_close($curl);
		
		return $res;
	}
}
